This invention relates to nodular nickel boron coatings on surfaces that requires a low coefficient of friction as well as a superior wear resistance. These coatings can be used as an improved substitute for wet lubricants. A lubricant can be incorporated in the nickel boron coating or can be coated onto the nickel boron coating. The final coatings provide improved wear resistance, corrosion resistance and lubricity.
Nickel boron coatings have been described in U.S. Pat. Nos. 6,319,308; 6,066,400 and 5,019,163. These references are incorporated by reference. Usually an electroless coating process as shown in these patents is used to make these coatings. These coatings have a nodular and columnar structure. U.S. Pat. No. 6,319,308 teaches that a lubricant particle can be co-deposited with the nickel boron coating.
The prior art has used wet lubricants to reduce the coefficient of friction and to reduce corrosion in firms. Usually firearms need to be cleaned and greased on a regular basis after firing. If not regularly greased, the firearm might jam or misfire.
The use of wet lubricants presents a problem for soldiers in the military. Wet lubricants attract grit or sand causing the firearms to jam requiring increased maintenance.
Phosphate reduced electroless coatings have been used on metal substrates such as firearms, to enhance corrosion resistance. These coatings do not possess the wear resistance and lubricity of the nodular nickel boron coatings.
An objective of the invention is to provide dry nodular nickel boron coating having improved lubricity. Another objective of this invention is to provide a substitute for wet lubricants, especially for firearms. Firearms as used in this application cover all types of weapons that use gun powder including rifles cannons and artillery. One objective being to increase the interval needed for reapplying the lubricant to the firearm parts.
The invention is directed to a nodular nickel boron coating having lubricating properties. Nodular and columnar boron coatings made by the above methods disclosed in the above patents have a low coefficient of friction. The above process results in a columnar structure with nodules in the surface layer. Nodules can be produced in other nickel coatings by blasting the surface with hard particles to form the nodules. Using blasting to form the nodules produces an inferior coating in contrast to the electroless nickel boron coatings having a columnar structure.
A lubricant can be introduced to the nickel boron coating by co-depositing a lubricant particle with the nickel boron or after treating the nickel boron coating with a dry lubricant. A variety of techniques exist for the treatment such as blasting the lubricant into the coating with high pressure or burnishing the dry lubricant into the nickel boron surface with a tumbling bowl or by rubbing the dry particle into the nickel boron surface. Examples of dry lubricants are tungsten disulfide or moly disulfide or PTFE (Teflon, trademark)).